Change: [Network] Update server's NetworkServerGameInfo only when needed

Split the updating in a "static" version that only needs to be called when a new map is loaded or some settings are changed, and a "dynamic" version that updates everything that changes regularly such as the current game date or the number of spectators.

src/network/network_func.h

@@ -68,6 +68,7 @@ void NetworkServerDailyLoop();
 void NetworkServerMonthlyLoop();
 void NetworkServerYearlyLoop();
 void NetworkServerSendConfigUpdate();
+void NetworkServerUpdateGameInfo();
 void NetworkServerShowStatusToConsole();
 bool NetworkServerStart();
 void NetworkServerNewCompany(const Company *company, NetworkClientInfo *ci);